JP2004-172028A discloses a conventional fuel cell system that maintains an output voltage of a fuel cell stack at a high voltage during idle stop.
However, it was found out that a problem occurs that the output voltage is lowered transitionally at the time of recovery from the idle stop when the output voltage of the fuel cell stack is maintained at the high voltage during the idle stop.
The present invention is made in view of such a problem, and it is an object to suppress the output voltage from being lowered at the time of the recovery from the idle stop.